The blockade of CD137-CD137L interactions impairs CXCR4-mediated migration of CTCL tumor cells. (A-B) Hut78 and MyLa cells (1.0 × 10⁶ per well) were cultured with anti-CD137L–neutralizing antibody (5 μg/mL) for 24 or 48 hours. CXCR4 expression was evaluated by flow cytometry (A), and quantitative RT-PCR (B). The mean fluorescent intensity (MFI) ratio was determined as MFI of target molecule/MFI of isotype control. (C) Hut78 and MyLa cells were treated with anti-CD137L–neutralizing antibody (5 μg/mL) for 12 hours, and then assessed in a migration assay for 12 hours at 37°C with human CXCL12 protein (0, 50, or 100 ng/mL). The percentage of migrating cells relative to input was determined. (D) PBMCs from 6 SS patients (1.0 × 10⁶ per well) were cultured with anti-CD137L antibody (5 μg/mL) for 24 hours. CXCR4 expression on CD4⁺CD7⁻ T cells was evaluated by flow cytometry. MFI expression was normalized to the MFI expression of isotype-treated cells. Representative results are shown. Data are presented as mean plus or minus SD. *P < .05, **P < .01